Hose with improved resistance to deformation, and method

ABSTRACT

A hose resistant to deformation is described which includes the usual polymeric tube and outer cover, and at least one annular reinforcement layer of fiber bundles sandwiched between the tube and cover. A polymeric aqueous-insoluble continuous film impregnates the fiber bundles and binds the reinforcement to at least one of the cover and tube, the continuous polymeric film serving to unexpectedly stiffen the hose appreciably. A method for producing the hose is described wherein the adhesive film is formed by applying a latex dispersion to the hose tube and/or reinforcement.

BACKGROUND OF THE INVENTION

This invention relates to hose produced by the superposition ofpolymeric layers and reinforcement, adhered together as an integrallaminate.

There are a number of applications in which a hose must have sufficientbody to resist crushing, kinking or stretching. For example, mine waterhose and sewer cleaner hose must meet these criteria. In the past thishas been accomplished by selecting the tube and/or cover stock to havesufficient modulus to provide the stiffness needed for the particularapplication. Certain thermoplastic stocks have been used in thisrespect, such as the relatively expensive Hytrel (trademark).

It is a primary object of this invention to produce hose highlyresistant to deformation, using relatively inexpensive stocks which areformed of fairly soft or flexible materials which heretofore have notqualified for such use.

Representative of the prior art are U.S. Pat. Nos. 2,478,939 (Pape) and3,988,189 (Sullivan).

SUMMARY OF THE INVENTION

Briefly described, the deformation-resistant hose of the inventioncomprises a polymeric tube, a polymeric outer cover, at least oneannular reinforcement layer of fiber bundles sandwiched between the tubeand cover, and a continuous adhesive aqueous-insoluble polymeric filmimpregnating the fiber bundles and binding a reinforcement layer to atleast one of said cover and tube. The continuous polymeric film impartsstiffness to the hose compared to the same hose construction without thepolymeric film ("control") to the extent that a force increased by atleast 40 percent compared to the control is required to deform the hoseto one-half its original inside dimension according generally to ASTM D622 deformation test.

In another aspect, the invention pertains to a method for producing hoseresistant to deformation including the steps of (a) applying a filmforming adhesive latex dispersion to a polymeric tube; (b) twining atleast one reinforcement layer comprised of fiber bundles over thepolymeric tube whereby the latex dispersion impregnates interstices inthe fiber bundles; and (c) applying a polymeric cover over thereinforcement layer. The temperature at which the latex dispersion isapplied, or subsequently elevated to, exceeds the glass transitiontemperature of the latex dispersion, to thereby form a continuouspolymeric film which binds the reinforcement to at least one of the tubeor cover, and which binds fibers of the bundles together into anagglutinous stiffened mass.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention in its preferred embodiments will be more particularlydescribed in conjunction with the accompanying drawings, in which likenumerals designated like parts, and in which:

FIG. 1 illustrates a hose of the invention, partially in section andpartially telescoped to show its component layers;

FIG. 2 is a flow diagram showing schematically a method for producingthe hose of the invention; and

FIG. 3 depicts an enlarged sectional view along lines 3--3 of FIG. 1,showing portions of the hose wall under magnification of approximately200X.

PREFERRED EMBODIMENTS OF THE INVENTION

Referring first to FIG. 1, there is shown generally at 10 acylindrically shaped hose in accordance with the invention, having acylindrical core tube 12, an adhesive/stiffener layer 14, a firstreinforcement layer 16 telescoped thereover, optional second layers ofadhesive/stiffener 18 and telescoped reinforcement 20, and an outersheath or cover 22. As will be described in more detail hereinafter,particularly with respect to FIG. 3, at least one of the reinforcementlayers is formed of fiber bundles impregnated with theadhesive/stiffener in the form of an agglomerated polymeric filmsurrounding and interconnecting fibers together, to form a non-coherentagglutinous mass.

The tube 12 and cover 22 may be formed of the same or differentpolymeric material, chosen for the particular application from a widevariety of thermoplastic or rubber polymeric materials, such as naturaland synthetic rubbers, polyvinylchloride, polyurethane, polyamide,polyester, and the like. The sandwiched reinforcement layers 16 and 20are formed of fiber bundles such as yarns or other textile composed offilaments of polyester, rayon, aramid, polyamide or other reinforcementmaterial. The reinforcement may be in the form of braid, knit, spiral,wrap or the like.

The method of construction of the hose of FIG. 1 is illustrated in FIG.2. Core tube 12 may be extruded from a standard extruder 24. A thinadhesive layer 14 is then applied as a latex dispersion to the exteriorof tube 12 by dipping in tank 26 containing adhesive 14', althoughalternative coating operations such as brushing, spraying or wipingthrough an appropriate die would also be useful. The tube with annularadhesive coating 14 is then passed through reinforcing machine 28 whichtwines reinforcement 16 about the surface of the coated tube, in theform of braid, spiral, or the like. If the hose is to consist of onlythe single layer of reinforcement, the reinforced tube with adhesivelayer 14 may then enter a preheater 30, especially for the applicationof a thermoplastic cover thereover to enhance the bonding, and then to acustomary crosshead extruder 32 which applies the outer sheath 22 inknown manner. The hose if thermoplastic may then be taken up directly onreel 34, or alternatively if vulcanizable materials are used for thetube and/or cover, the hose may be cured first in vulcanization zone 36using customary heating methods, including lead press, open steam cure,microwave and fluidized bed.

Where multiple layers of reinforcement are to be twined onto the tube,the additional steps shown between A₁ and A₂ may be employed, with asmany replications as required. To produce the hose of FIG. 1, the tubeand first layer of reinforcement are dipped into a second adhesive bath38 containing adhesive 18' in the form of a latex dispersion whereby asecond thin layer 18 of adhesive material in accordance with theinvention is applied over reinforcement layer 16. The secondreinforcement layer 20 is twined over the reinforced tube with the aidof a second reinforcing machine 40. The double reinforced core tube maynow be preheated at 30, passed through extruder 32 to receive outercover 22, and be taken up on reel 34. If additional bonding is requiredbetween the outer reinforcement layer 20 and tube 22, the hose may passthrough a further adhesive dip applicator 42. The hose may also besubjected to other operations depending upon the nature of the polymericconstituents of the hose, such as a cooling tank, dryer or the like.

The invention is premised upon the use of adhesive layers 14, 18 whichare aqueous-insoluble and which form under the conditions ofmanufacturing a continuous adhesive polymeric film which impregnates thefiber bundles forming the reinforcement, and interstices between andwithin the fiber bundles, and which binds the reinforcement layer(s) toeither or both of the cover and tube. The properties of the resultantcontinuous polymeric film critically serve to stiffen the hose comparedto the same hose without the polymeric film ("control") to the extentthat a force increase by at least 40 percent compared to the control isrequired to deform the hose to one-half its original inside dimension(i.e., tube inside diameter) using American Society For Testing AndMaterials (ASTM) D 622, Deformation Test. More preferably a forceincreased by at least about 65 percent and most preferably by at leastabout 110 percent compared to the control is required to deform the hoseto one-half its original inside dimension per ASTM D 622 DeformationTest.

The adhesive/stiffener material of the invention must be anaqueous-insoluble, film forming polymeric material preferably applied asa latex dispersion. Generally, the dispersion is in the form of anemulsion, stabilized against coagulation, with a solids content usuallyin the range from about 35 percent to about 65 percent, more preferablyfrom about 50 percent to about 60 percent. A continuous polymeric filmwhich serves the critical dual purpose of an adhesive as well as astiffener is assured by applying the latex dispersion at a temperaturewhich exceeds the glass transition temperature of the polymer of thelatex, or by subsequently elevating the temperature above the glasstransition temperature to cause continuous film formation. While thefilm produced has a dramatic stiffening effect, it will still possess asubstantial degree of flexibility to permit the hose to be flexed whileassuring coalescence of the polymer, and this can be provided in knownmanner by increasing the drying temperature, by polymerizing duringmanufacture of the latex with a suitable softening comonomer or byadding plasticizer, or a combination of these.

To achieve the balance of stiffness and flexibility required, it ispreferred that the adhesive polymer or copolymer have a modulus at 100percent elongation of at least about 200 psi, more preferably at leastabout 500 psi and more preferably at least about 750 psi. For a givenpolymer, its modulus can be increased generally by raising the fusiontemperature and fusion time, as is known. Adhesive polymers which may beapplied in latex form, and which are particularly preferred inaccordance with the invention include acrylic, vinyl chloride, vinylchloride-acrylic copolymers, vinylidene chloride, nitrile andstyrene-butadiene latexes. A line of such adhesive latexes are offeredby the B. F. Goodrich Company under the trademarks Good-rite, Geon andHycar. Most preferred are latexes based on copolymers of vinyl chlorideas the resin, preferably plasticized, and having glass transitiontemperatures T_(g) of generally less than about 110° F., more preferablyless than about 72° F. (room temperature).

EXAMPLE

As a specific example of a hose of the form of FIG. 1 constructed inaccordance with the invention, a core tube 12 of one inch nominalinternal diameter of polyvinyl chloride was processed by passing it atroom temperature through a wiping die containing a bath of Geon 576(trademark), a plasticized vinyl chloride copolymer having a glasstransition temperature T_(g) of 68° F. and a modulus of 900 psi at roomtemperature. The flow rate was adjusted to achieve an adhesive coatingof approximately 0.01 to about 0.02 inches thick. The tube with coating14 was then introduced into a first braider deck 28 in which polyesterof tight pack, 2 ends per braid, and 5500 denier was braided on thecoated tube. The thus reinforced tube was then passed through a secondwiping die applying an additional coating 18 of Geon 576 PVC latex, andthen the hose was introduced into a second braiding station 40 at whicha second braid 20 of identical construction to the first braid 16 wastwined onto the hose preform. The thus reinforced and coated tube wasintroduced into preheater 30 held at a temperature of 750° F., whereinthe outer polyester braid 20 was softened. The hose preform then wasintroduced into crosshead extruder 32 which applied a cover layer ofpolyurethane (Estane 58360), and the completed hose wound up on reel 34.This hose shall be designated Sample A.

The same procedure and materials were used to produce three additionalsamples, except the adhesive treatment was varied as follows. In SampleB Geon 450×20 (trademark), a vinyl chloride-acrylic copolymer having aglass transition temperature of 50° F., and a modulus of 220 psi at roomtemperature was used. Sample C employed Geon 351 (trademark), anonplasticized vinyl chloride copolymer having a glass transitiontemperature of 142° F., and Sample D was a control in which no adhesivewas applied. The adhesive of Sample C, as evidenced by photomicrograph,formed a cracked, discontinuous film since the temperature ofapplication was not above the glass transition temperature of the resin.Each of the samples were tested for adhesion. While all the samplesdemonstrated good adhesion between the cover 22 and outer reinforcementbraid 20, the control evidenced no measurable adhesion between the tubeand first reinforcement layer 16, and between reinforcement layers 16and 20. Sample C evidenced no measurable adhesion between the respectivereinforcement layers 16 and 20, apparently because no continuous filmwas formed, although good adhesion between the tube and firstreinforcement layer was measured. Samples A and B evidenced adhesions ofat least one pound per square inch both between the tube andreinforcement, and between the respective reinforcement layers.

In a second test, each of the samples were deformed to 50 percent of itsoriginal inside dimension (i.e., 1/2 inch), in accordance with theapparatus and procedure of ASTM D 622 Deformation Test. For improvedcomparative purposes, a 1/2 inch feeler gauge was employed rather thanthe 1/4 inch feeler gauge called for in the test specification. The testresults showed that a force of 52 pounds was required to deform Sample Ato 1/2 of its original inside dimension, Sample B required 35 pounds,Sample C required 40 pounds, and the control required only 24 pounds.

A collapse test in which each of the samples were bent around fourdifferent mandrels (6 inch radius, 4 inch radius, 3 inch radius, and 2inch radius respectively) showed Sample A to be most resistant tocollapse about the respective mandrels, Sample B next best, with thecontrol (Sample D) and Sample C being approximately the same, bothinferior to Samples A and B.

In FIG. 3, a drawing taken from a photomicrograph (100X SEM) shows theouter surface of tube 12, first braid layer 16, and the impregnated Geon576 adhesive/stiffener, taken from the hose of Sample A referred to inthe above tests. As seen in FIG. 3, the adhesive impregnates intersticeswithin the fiber bundle shown generally at 16, and forms with the fiberbundle an agglomerated, non-coherent agglutinous mass of adhesivestrings or particles 14 interconnecting individual fibers of the bundleas a crack-free film, and also forming at least a partial coating on thefiber surfaces.

Thus, with the hose of the subject invention it is possible to use tubestock (e.g., PVC) and cover materials which have desired properties,such as low temperature flexibility, and which are relativelyinexpensive, while still achieving a resultant hose highly resistant todeformation. The stiffness is achieved without having to use theexpensive, high modulus stocks of the prior art, such as Hytrel (apolyester compound).

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:
 1. A hose resistant to deformation comprising apolymeric tube, a polymeric outer cover, at least one annularreinforcement layer of fiber bundles sandwiched between the tube andcover, and a continuous adhesive aqueous-insoluble polymeric filmimpregnating such fiber bundles and binding a reinforcement layer to atleast one of said cover and tube, the continuous polymeric film servingto stiffen the hose compared to the same hose construction without thepolymeric film ("control") to the extent that a force increased by atleast about 40 percent compared to the control is required to deform thehose to one-half its original inside dimension using ASTM D 622deformation test.
 2. The hose of claim 1 wherein the fiber bundles andpolymeric film impregnant form an agglomerated, noncoherent agglutinousmass.
 3. The hose of claim 1 wherein the hose tested under ASTM D 622has an inside dimension of one inch nominal, deformed to one-half inchinside dimension under the test.
 4. The hose of claim 1 wherein thepolymeric film is formed of a copolymer of vinyl chloride.
 5. The hoseof claim 1 wherein the tube and cover are formed of thermoplasticpolymers.
 6. A crush-resistant thermoplastic hose comprising a normallyflexible thermoplastic tube, a normally flexible thermoplastic outercover, and at least one annular reinforcement layer of fiber bundlessandwiched between the tube and cover, and a continuous adhesiveaqueous-insoluble polymeric film impregnating such fiber bundles andbinding a reinforcement layer to at least one of said cover and tube,the continuous polymeric film serving to stiffen the hose compared tothe same hose construction without the polymeric film ("control") to theextent that a force increased by at least about 40 percent compared tothe control is required to deform the hose to one-half its originalinside dimension using ASTM D 622 deformation test.
 7. The hose of claim6 including at least two layers of reinforcement, one telescoped overthe other, and a layer of said continuous polymeric film interposedbetween and mutually binding adjacent layers of reinforcement.
 8. Thehose of claim 7 wherein said reinforcement is in the form of braidedtextile material.
 9. A hose resistant to deformation comprising apolymeric tube having a given inside dimension, a polymeric outer cover,at least one annular reinforcement layer of fiber bundles sandwichedbetween the tube and cover, and a continuous adhesive aqueous-insolublepolymeric film impregnating such fiber bundles to form an agglutinousmass of adhesive strings interconnecting individual fibers of thebundle, and the film serving to bind a reinforcement layer to at leastone of said cover and tube, the continuous polymeric film serving tostiffen the hose compared to the same hose construction without thepolymeric film ("control") to the extent that a force increased by atleast about 40 percent compared to the control is required to deform thehose to one-half its original inside dimension using ASTM D 622deformation test.
 10. The hose of claim 9 wherein the continuousadhesive aqueous-insoluble film at least partially coats directly on thefiber surfaces of the fiber bundles.
 11. The hose of claim 9 wherein thefiber bundles are formed of a multitude of microfibers.
 12. A hoseresistant to deformation comprising a polymeric tube, a polymeric outercover, at least one annular reinforcement layer of fiber bundles formedof a multitude of fine fibers sandwiched between the tube and cover, anda continuous adhesive aqueous-insoluble polymeric film impregnating suchfiber bundles and adhesively interconnecting individual fibers of thebundle as a substantially crack-free film, and the adhesive film bindinga reinforcement layer to at least one of said cover and tube, thecontinuous polymeric film serving to stiffen the hose compared to thesame hose construction without the polymeric film ("control") to theextent that a force increased by at least about 40 percent compared tothe control is required to deform the hose to one-half its originalinside dimension using ASTM D 622 deformation test.
 13. A hose resistantto deformation comprising a polymeric tube, a polymeric outer cover, atleast one annular reinforcement layer of fiber bundles sandwichedbetween the tube and cover, and a continuous adhesive aqueous-insolublepolymeric film having a modulus at 100 percent elongation of at leastabout 200 psi and a glass transistion temperature T_(g) of less thanabout 72° F. impregnating such fiber bundles and adhesivelyinterconnecting individual fibers of the bundle, and binding areinforcement layer to at least one of said cover and tube, thecontinuous polymeric film serving to stiffen the hose compared to thesame hose construction without the polymeric film ("control") to theextent that a force increased by at least about 65 percent compared tothe control is required to deform the hose to one-half its originalinside dimension using ASTM D 622 deformation test.
 14. The hose ofclaim 13 wherein the polymeric film was formed from a film forming latexdispersion applied to impregnate interstices within the fiber bundles atsubstantially room temperature (72° F.).